I know I've heard you only need to take one pet down the symol hole....but I always take all 4 of ours at once. Well, today, I was doing my daughter's. She already has the avie for it, too...bugger! Anyway, I took her first pet, second, then on the third one we got this:

Something has happened!
Ohhh how cute. It seems charm has got a Larnikin in its mouth. Have you been feeding it lately?

This was about 12:40 PM NST. But this is the kicker. The Charm angelpuss petpet wasn't even the ACTIVE petpet! It was on her FIRST pet I took down! So, any of your petpets can snag something! Even one you have already taken down!